Reactive Extraction of Isobutyric Acid from Water Using Trioctyl Amine in Different Toxic and Nontoxic Diluents

In this work, the reactive extraction of isobutyric acid (IBA) is reported for the first time over the temperature range of 298–318 K. Trioctylamine (TOA) in eight different diluents was studied. For reducing the harmful effect of TOA on living microorganisms in the fermentation broth, nontoxic sunflower and soybean oils were used along with six other petrochemical-based diluents. For physical extraction, the distribution coefficient (KDdil) appeared reasonably high. TOA enhanced the distribution constants. In reactive extraction, the extraction efficiencies were 82–93% for decanol, 80–88% for octanol, 78–87% for hexanol, 76–86% for MIBK, 75–85% for toluene, 75–83% for petroleum ether, 73–82% for sunflower oil, and 72–81% for soybean oil. The sequence of the KDoverall was decanol > octanol > hexanol > MIBK > toluene > petroleum ether > sunflower oil > soybean oil. The obtained KDchem/KDphy > 1.0 confirmed the dominance of the chemical extraction over the physical extraction. The complexation reaction stoichiometry and equilibrium reaction constants were estimated by using the differential evolution technique. Different thermodynamic parameters like enthalpy and entropy changes were determined and analyzed. (ΔH)mass tr values showed that mixing of the aqueous and organic phases is the most difficult in sunflower oil and easiest in decanol.